Interannual controls on oxygen isotope variability in Asian monsoon precipitation and implications for paleoclimate reconstructions
Interannual controls on oxygen isotope variability in Asian monsoon precipitation and implications for paleoclimate reconstructions
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DOI：
10.1002/2015jd024683
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发表时间：
2016-07
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影响因子：
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通讯作者：
H. Yang;K. Johnson;M. Griffiths;K. Yoshimura
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作者：
H. Yang;K. Johnson;M. Griffiths;K. Yoshimura
亚洲季风洞穴δ18O的轨道至千年尺度的变化已被广泛解释为季风强度和/或降雨量的记录。为了评估这些机制和其他机制对高频 δ18O 变化的影响，我们利用光谱推动的同位素大气环流模型的模拟与仪器气候数据相结合，研究受亚洲季风影响的四个关键洞穴位置对年际降水 δ18O (δ18Op) 变化的气候控制：阿曼的昆夫洞穴； Mawmluh 洞穴，印度；老挝 Tham Mai 洞；和中国的东阁洞。与仪器气候数据的比较表明，δ18Op年际变化与四个站点的当地降水量关系较弱，而主要受热带印度太平洋地区大范围季风强度和上游降水的控制，从而影响传入水分的δ18O。与海面温度和降水的空间相关性、综合分析和时间序列分析表明，厄尔尼诺-南方涛动（ENSO）在调节该地区降水δ18Op年际变率方面也发挥着关键作用，特别是在印度北部和东南亚，厄尔尼诺年期间δ18Op正异常反映了来自附近孟加拉湾的高δ18O水分的贡献增加。在整个亚洲季风地区的高分辨率代理记录中看到的δ18O的年际到年代际变化一致，可能记录了季风强度和上游降雨，而印度北部和东南亚的记录中与ENSO相关的变化可能最强，当弱季风和厄尔尼诺现象同时发生时，预计会出现最大的异常。
Orbital to millennial‐scale variations in Asian monsoon speleothem δ18O have been widely interpreted as records of monsoon intensity and/or rainfall amount. To assess the influence of these and other mechanisms on higher‐frequency δ18O variability, we utilize simulations from a spectrally nudged isotope‐enabled general circulation model coupled with instrumental climate data to investigate the climatic controls on interannual precipitation δ18O (δ18Op) variability at four key cave locations affected by the Asian monsoon: Qunf Cave, Oman; Mawmluh Cave, India; Tham Mai Cave, Laos; and Dongge Cave, China. Comparison with instrumental climate data shows that interannual δ18Op variations are only weakly related to local precipitation amount at the four sites and are instead controlled primarily by large‐scale monsoon intensity and upstream precipitation over the tropical Indo‐Pacific region, which influence the δ18O of incoming moisture. Spatial correlations with sea surface temperature and precipitation, composite analyses, and time series analyses show that the El Niño–Southern Oscillation (ENSO) also plays a key role in modulating interannual precipitation δ18Op variability in the region, especially in northern India and Southeast Asia, with positive δ18Op anomalies during El Niño years reflecting increased contribution of high δ18O moisture from the nearby Bay of Bengal. Coherent interannual to decadal δ18O variations seen in high‐resolution proxy records from across the Asian monsoon region, likely record monsoon intensity and upstream rainout, whereas ENSO related variability is likely to be strongest in records from northern India and Southeast Asia, with the largest anomalies expected when weak monsoons and El Niño occur together.